The Ring gear assembly is 108 tooth approx. 9″ diameter and can be drilled to fit most common rotorheads for an additional $10.00 USD
If drill-to-fit is desired, state rotorhead model and attach a photo if possible.
Note: Ring gear assemblies come with a 2.0625″ (2 1/16″) +- center hole, except for RFD (Dominator) rotorheads which use a 3.875″ (3 3/4″) hole. Custom hole diameters larger than 2.0625″ are available for an extra fee.